292 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



tially rotted reeds and flags were floating. The nests were usually 

 very flimsy affairs, a few loosely arranged bits of reeds and flags 

 serving to raise the eggs an inch or so above the water. Often the 

 eggs were laid in slight depressions in this floating rubbish, with no 

 apparent attempt at nest building, where the eggs were wet and 

 nearly awash. In Saskatchewan we found a small colony on June 

 24, 1906, breeding in a wet, grassy meadow where the water was 

 only a few inches deep. The nests all contained fresh eggs and 

 were merely small piles of rubbish floating among the scattered 

 growth of short green meadow grass. I have several sets of eggs 

 in my collection, taken by Mr. Gerald B. Thomas in Livermore, 

 Iowa, during the last week in July. The nests were located in 

 sunken muskrat houses, old grebe nests, and an old coot nest. Nests 

 of the black tern often have substantial foundations of water mosses 

 and other soft vegetable substances, which some writers seem to 

 think are built by the birds. I think, however, that the black tern 

 never gathers any such materials and that these foundations are 

 either old grebes' nests, or merely floating masses of muck, selected 

 by the terns, on which only the suj)erstructure of the nest is built 

 by them, 



Mr. J. C. Knox (1899), who has seen the nest-building process, 

 gives the following account of it: 



I had always before believed that the black tern merely hollowed out a 

 nest on a bog and deposited her eggs there, but I was now undeceived. As I 

 was walking along I happened to glance upward and saw a black tern with 

 something in her bill. She was coming directly toward me, so I dropped down 

 out of sight in a clump of green rushes. Just in front of me was the remains 

 of an old muskrat house, now little more than a bog — a capital place for a 

 tern's nest. Here she alighted and deposited her weed stem on the edge of a 

 little hollow near one edge of the bog; then she flew away again, but soon 

 returned with another weed and deposited that. I watched her for half an 

 hour, and during that time she made 14 trips to the nest, bringing material each 

 time, and twice her mate came with her. When I left the nest was not 

 completed, but I think she had quit nest building for that morning. Many of the 

 eggs of this species are laid on a bare bog, with no nest at all, but in this 

 instance a nest was made and the materials, which could have been had directly 

 at hand, were brought from a distance. 



Occasionally nests of this species are placed on pieces of driftwood 

 or boards where they are very conspicuous, but usually they are very 

 hard to see, as both nests and eggs match their surroundings per- 

 fectly. 



Eggs. — The eggs of the black tern are very handsome and are 

 subject to considerable variation. Many of these resemble the eggs 

 of some of the Limicolae, as they are often somewhat pointed. The 

 average shape is ovate, with a decided tendency in some specimens 

 toward ovate pyriform. The shell is thin and has a dull luster. 



